The present invention relates to motor controllers and more particularly to a method of controlling a rotary machine used in a hybrid vehicle and a controller therefor.
In the hybrid vehicle or an electro-mobile using a motor in the drive system of a vehicle, for the sake of controlling the torque or revolution speed of the motor (for example, a DC brushless motor), the phase of voltage applied to an armature needs to be controlled in accordance with the position of a magnetic pole of a rotor. Accordingly, in this type of motor (DC brushless motor), a magnetic pole position sensor for detection of the rotor's magnetic position is provided so that the phase of the voltage applied to the armature may be manipulated in accordance with a magnetic pole position detected by the magnetic pole position sensor. The magnetic pole position sensor as above is constructed of a resolver, an encoder and a Hall device. In controlling an AC motor provided with the magnetic pole position sensor, an error will often develops between a detected magnetic pole position and an actual magnetic pole position owing to positioning during assemblage of the magnetic pole position sensor, aging deterioration and detection accuracy of the magnetic pole position sensor per se as well. When the phase of voltage is manipulated using the detected magnetic pole position in the presence of the error as above, the motor will suffer degradations in power factor and efficiency. In addition, even if the torque command value to the motor is zero, a current will flow, so that unnecessary power running and regenerative torque are sometimes generated and the battery undergoes unwanted charge or discharge.
In an invention for correction of the phase error in the magnetic pole position sensor as disclosed in a related art JP-A-2001-211698, the magnetic pole position is estimated on the basis of a signal for synchronization of motor current with PWM signal in order to correct the revolution sensor for its position error. In the related art, a differential value of motor current during three-phase short-circuit is calculated to determine an estimated value of magnetic pole position.